Question

There is a small air bubble inside a thick lens of glass as shown in the figure. What is the distance between the images of the air bubble as seen by two observers, one in air and other in water?
(Given radius of curved surface is 5 cm)

• A. 1 cm
• B. 9 cm
• C. 1.5 cm
• D. 4 cm

Answer 1

The correct option is A 1 cm

For observer in air:
Bubble and image coincides with each other
For observer in water :
$d^{\prime }=\frac{d}{{\mu }_{rel}}$
$=\frac{d}{\frac{{\mu }_g}{{\mu }_w}}$
$=\frac{9}{\left(\frac{3}{2}\right)}\left(\frac{4}{3}\right)$
=8cm
14-(5+8)=1cm